Various materials have been used as automobile headliners. My U.S. Pat. No. 4,695,501 discloses thermoformable composite panels comprised of a core made of one or more layers of synthetic resin foam, for example, styrene/maleic anhydride copolymer synthetic resin. The core is covered on its opposite surfaces by fabric layers which are bonded to the core layers by adhesive layers. At least one of the fabric layers is impregnated with a thermoplastic or thermosetting resin.
Automobile headliners must be able to withstand elevated temperatures without sagging or buckling. The automobile headliner panels of U.S. Pat. No. 4,695,501 are effective to withstand temperatures of up to about 200.degree. F., without significant sagging or buckling.
I have discovered that the heat resistance of the panels can be improved by incorporating fibers, especially chopped fiberglass strands, in the foam core, particularly a styrene/maleic anhydride copolymer synthetic resin foam core. Although many polymers having higher heat resistance than styrene/maleic anhydride copolymers are known, they are more difficult to thermoform and articles made therefrom in three dimensionally contoured configurations tend to be objectionably stiff or boardy and they exhibit reduced sound-absorbing properties. Surprisingly, and contrary to expectations, I have found that the incorporation of fibers, especially randomly distributed, short, discrete, discontinuous glass fibers, in the foamed styrene/maleic anhydride copolymer synthetic resin does not detrimentally affect the molding of the foam core, the thermoforming of the thermoformable composite panel made using that core or the sound-absorbing properties of the finished panel.